In various applications it is desirable to remove carbon monoxide from gases and this is typically achieved by passing the gases through a hopcalite filter bed. Hopcalite is a specially prepared filtering material made of a miture of copper and manganese oxides, which filtering material functions as a room temperature catalyst to promote oxidation of carbon monoxide to carbon dioxide.
In processes currently used to produce hopcalite filtering materials suitable chemicals are allowed to react in solution to form the active ingredients which precipitate out as a sludge. This product is then rinsed, dried and pressed to form a block. The product is then crushed and sieved. Prior to calcining the product is known as "green" hopcalite. The sieved product, which typically passes through a 6 mesh screen but not through a 14 mesh screen, is calcined for several hours in a hot oven. Calcining transforms the product to its final form. The resultant product is then assembled into a filter bed with appropriate screens and/or other containment to prevent it with spilling or being settled by vibration. While the filter bed made by this process performs in a very satisfactory manner it requires a tedious assembly process.
Another process for forming a hopcalite filter pad is to mix ceramic fibers and hopcalite dust so that the lightweight dust particles are loosely supported by the fibers. The hopcalite dust is typically that product which will pass through a 100 mesh screen. The resultant fiber and dust mixture are also supported within a filter canister by layering the fiber and hopcalite dust mixture between screens or filter pads. While the hopcalite filter pad utilizing hopcalite dust has the advantage in that it is lighter and uses less material for the volume used, this hopcalite filter construction does not perform as well as the pure hopcalite filter construction of comparable volume, and also this form is somewhat difficult to assemble.